#307bc9
a balanced, vivid blue · cool · closest name: Steel Blue
At a glance
Every number on this page in one read: what #307bc9 is made of, how bright it looks, and which way it leans.
Reads cool. Warm and cool siblings keep the same lightness, so you can swap one in without redoing your contrast maths.
Every format
| HEX | #307bc9 |
| RGB | rgb(48, 123, 201) |
| HSL | hsl(211, 61%, 49%) |
| CMYK | cmyk(76%, 39%, 0%, 21%) |
| LAB | lab(50.7 4.0 -47.1) |
| LCH | lch(50.7 47.2 274.9) |
| OKLCH | oklch(0.575 0.141 252.4) |
| Decimal | 3177417 |
| Display P3 | color(display-p3 0.188 0.482 0.788) |
Copy-ready code
/* CSS */
color: #307bc9;
background-color: #307bc9;
/* Tailwind (arbitrary) */
class="text-[#307bc9] bg-[#307bc9]"
/* SCSS */
$brand: #307bc9;
/* SwiftUI */
Color(red: 0.188, green: 0.482, blue: 0.788)
/* Android */
Color.parseColor("#307bc9")
/* Flutter */
Color(0xFF307BC9)
/* Python / OpenCV (BGR) */
(201, 123, 48)Best text color
Only one of black and white can be right. This is the one, with the number that proves it.
Accessibility — WCAG contrast
Color scale — 50 to 950
A Tailwind-shaped ramp built around this exact hex. #307bc9 is pinned to step 600; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.
:root {
--brand-50: #F4F7FB;
--brand-100: #E8F0F7;
--brand-200: #CCDDF0;
--brand-300: #A4C6E9;
--brand-400: #77AADF;
--brand-500: #4A8DD4;
--brand-600: #307bc9;
--brand-700: #2765A5;
--brand-800: #1F5184;
--brand-900: #1B3D60;
--brand-950: #11263C;
--brand: #307bc9;
--brand-ink: #000000;
}Colors that work with #307bc9
Not a palette — a role sheet. Each swatch answers one question you will hit while building the component.
Surface, border, heading and body all derive from this one hue, so the screen stays coherent without a second palette.
Lightness flips, hue holds. The accent stays the anchor in both themes.
How to use #307bc9
Derived from its contrast, chroma and lightness — not from taste.
- ✓Headings from 24px up on white
- ✓Text and icons on dark surfaces
- ✓Primary buttons and calls to action
- ✓Focus rings, active and selected states
- ✓Brand accents, badges and data highlights
- ⚠Small text on white — under 4.5:1
- ⚠Full-page backgrounds — tiring over long sessions
- ⚠Pairing with a same-lightness hue — edges vibrate
Similar colors
One move away from this hex in each direction. Every swatch is its own page.
Color relationships
The wheel positions with their names attached, so you can grab the one you actually need.
| Complementary | #C97E30 | Directly opposite — maximum tension | |
| Analogous left | #30C7C9 | Neighbour, quieter | |
| Analogous right | #3230C9 | Neighbour, quieter | |
| Split-complement 1 | #C93230 | Contrast without the clash | |
| Split-complement 2 | #C7C930 | Contrast without the clash | |
| Triadic 1 | #C9307B | Even thirds — balanced and loud | |
| Triadic 2 | #7BC930 | Even thirds — balanced and loud | |
| Tetradic | #C930C7 | Fourth corner of the square scheme |
RGB percentages
CMYK percentages
Color previews
#307bc9 text on a black background
contrast 4.80:1
#307bc9 text on a white background
contrast 4.37:1
CSS3 live lab
The quick brown fox
color: #307bc9;
background-color: #307bc9;
Glowing headline
text-shadow: 2px 2px 8px #307bc9;
Soft neon halo
text-shadow: 0 0 14px rgba(48, 123, 201, 0.45);
box-shadow: 0 12px 32px -8px rgba(48, 123, 201, 0.45);
border: 3px solid #307bc9; background: linear-gradient(135deg, #307bc9, #4B30C9);
Monochromatic scale
Palettes built from #307bc9
Shades — darker
Tints — lighter
Color harmonies
Nearest named colors
Ranked with CIEDE2000 across all 139 CSS keywords. Under ΔE 2 the eye stops telling them apart; over ΔE 10 they are plainly different colors.
Closest color with a full write-up: Steel Blue (#4682b4) — ΔE2000 3.8 away, with its history, psychology and brand usage.
#307bc9 in the real world
Where a color in this family tends to land, and the interface roles it is usually asked to play.
Converts to four-color process without much drama. Proof it anyway.
#307bc9, answered
What color is #307bc9?
#307bc9 is a balanced vivid blue, closest to Steel Blue (ΔE2000 3.8). It sits at 211° on the hue wheel with 61% saturation and 49% lightness, which reads as cool.
What is the RGB value of #307bc9?
rgb(48, 123, 201) — 48 red, 123 green and 201 blue out of 255, or 18.8% / 48.2% / 78.8% by channel.
Is #307bc9 a light or a dark color?
It is a mid-tone. Relative luminance is 0.1901 and perceived brightness is 47%, so black text on it reaches 4.80:1.
Should I use black or white text on #307bc9?
Black. It scores 4.80:1 against #307bc9, versus 4.37:1 for white — AA at any size.
What is the complementary color of #307bc9?
#C97E30 sits directly opposite on the wheel. Softer options are the split-complements #C93230 and #C7C930, which give the same contrast with far less vibration.
What colors go well with #307bc9?
For interface work: #F4F7FA as the surface, #C0D6ED for borders, #4B729B for secondary text, #CE552B as an accent and #193F67 for hover and pressed states. For a palette, the analogous pair #30C7C9 and #3230C9 stays calm, while #C97E30 is the loudest partner.
What is #307bc9 in CMYK for printing?
cmyk(76%, 39%, 0%, 21%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.
Is #307bc9 warm or cool?
Cool — it scores 100 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #3043C9; nudged cooler, #296DB7.